U.S. patent application number 16/376508 was filed with the patent office on 2019-10-10 for gas-phase selective etching systems and methods.
This patent application is currently assigned to Applied Materials, Inc.. The applicant listed for this patent is Applied Materials, Inc.. Invention is credited to Geetika Bajaj, Prerna Sonthalia Goradia, Nitin Ingle, Zihui Li, Robert Jan Visser.
Application Number | 20190311909 16/376508 |
Document ID | / |
Family ID | 68096547 |
Filed Date | 2019-10-10 |
United States Patent
Application |
20190311909 |
Kind Code |
A1 |
Bajaj; Geetika ; et
al. |
October 10, 2019 |
GAS-PHASE SELECTIVE ETCHING SYSTEMS AND METHODS
Abstract
Systems and methods of etching a semiconductor substrate may
include flowing an oxygen-containing precursor into a substrate
processing region of a semiconductor processing chamber. The
substrate processing region may house the semiconductor substrate,
and the semiconductor substrate may include an exposed
metal-containing material. The methods may include flowing ammonia
into the substrate processing region at a temperature above about
200.degree. C. The methods may further include removing an amount
of the metal-containing material.
Inventors: |
Bajaj; Geetika; (New Delhi,
IN) ; Visser; Robert Jan; (Menlo Park, CA) ;
Ingle; Nitin; (San Jose, CA) ; Li; Zihui;
(Santa Clara, CA) ; Goradia; Prerna Sonthalia;
(Mumbai, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Materials, Inc. |
Santa Clara |
CA |
US |
|
|
Assignee: |
Applied Materials, Inc.
Santa Clara
CA
|
Family ID: |
68096547 |
Appl. No.: |
16/376508 |
Filed: |
April 5, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62653933 |
Apr 6, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 21/31116 20130101;
H01L 21/3065 20130101; C23F 1/12 20130101; H01L 21/32135 20130101;
H01L 21/32136 20130101; H01L 21/02244 20130101 |
International
Class: |
H01L 21/3065 20060101
H01L021/3065; H01L 21/3213 20060101 H01L021/3213; H01L 21/311
20060101 H01L021/311 |
Claims
1. A method of etching a semiconductor substrate, the method
comprising: flowing an oxygen-containing precursor into a substrate
processing region housing the semiconductor substrate, wherein the
semiconductor substrate includes an exposed metal-containing
material; flowing ammonia into the substrate processing region at a
temperature above about 200.degree. C.; and removing an amount of
the metal-containing material.
2. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor is configured to react with
the metal-containing material to produce a modified
metal-containing material.
3. The method of etching a semiconductor substrate of claim 2,
wherein the nitrogen-containing precursor is configured to react
with the modified metal-containing material to produce a volatile
complex.
4. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor comprises one or both of
water or ozone.
5. The method of etching a semiconductor substrate of claim 1,
wherein the pressure within the substrate processing region is
maintained above or about 10 Torr.
6. The method of etching a semiconductor substrate of claim 5,
wherein the pressure within the substrate processing region is
maintained above or about 100 Torr.
7. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor and the nitrogen-containing
precursor are flowed sequentially into the substrate processing
region.
8. The method of etching a semiconductor substrate of claim 7,
further comprising holding for a first period of time subsequent
flowing the oxygen-containing precursor and prior to flowing the
nitrogen-containing precursor.
9. The method of etching a semiconductor substrate of claim 8,
wherein the first period of time is between about 5 seconds and
about 30 seconds.
10. The method of etching a semiconductor substrate of claim 7,
further comprising holding for a second period of time subsequent
flowing the nitrogen-containing precursor.
11. The method of etching a semiconductor substrate of claim 10,
wherein the second period of time is between about 10 seconds and
about 60 seconds.
12. The method of etching a semiconductor substrate of claim 1,
wherein the oxygen-containing precursor and the nitrogen-containing
precursor are halogen free, and wherein the method comprises a
plasma-free process.
13. The method of etching a semiconductor substrate of claim 1,
wherein the method is performed at a temperature of greater than or
about 300.degree. C.
14. The method of etching a semiconductor substrate of claim 1,
wherein the process is performed in a continuous operation, and
wherein the process removes greater than or about 4 .ANG./min.
15. The method of etching a semiconductor substrate of claim 1,
wherein the metal-containing material comprises titanium
nitride.
16. A method of etching a semiconductor substrate, the method
comprising: removing a native oxide from a metal-containing
material exposed on the semiconductor substrate; flowing ozone into
a substrate processing region housing the semiconductor substrate;
holding for a first period of time greater than or about 1 second;
flowing a nitrogen-containing precursor into the substrate
processing region; holding for a second period of time greater than
or about 1 second; and removing an amount of the metal-containing
material.
17. The method of etching a semiconductor substrate of claim 16,
further comprising flowing additional nitrogen-containing precursor
into the substrate processing region.
18. The method of etching a semiconductor substrate of claim 16,
wherein the method removes at least about 4 .ANG. per minute during
the method.
19. The method of etching a semiconductor substrate of claim 16,
wherein the nitrogen-containing precursor is ammonia.
20. The method of etching a semiconductor substrate of claim 16,
wherein the pressure is maintained at greater than or about 100
Torr during the method.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/653,933, filed Apr. 6, 2018, and which is hereby
incorporated by reference in its entirety for all purposes.
TECHNICAL FIELD
[0002] The present technology relates to semiconductor systems,
processes, and equipment. More specifically, the present technology
relates to systems and methods for selectively etching
metal-containing materials utilizing a gas-phase etching
process.
BACKGROUND
[0003] Integrated circuits are made possible by processes which
produce intricately patterned material layers on substrate
surfaces. Producing patterned material on a substrate requires
controlled methods for removal of exposed material. Chemical
etching is used for a variety of purposes including transferring a
pattern in photoresist into underlying layers, thinning layers, or
thinning lateral dimensions of features already present on the
surface. Often it is desirable to have an etch process that etches
one material faster than another facilitating, for example, a
pattern transfer process. Such an etch process is said to be
selective to the first material. As a result of the diversity of
materials, circuits, and processes, etch processes have been
developed with a selectivity towards a variety of materials.
[0004] Etch processes may be termed wet or dry based on the
materials used in the process. A wet HF etch preferentially removes
silicon oxide over other dielectrics and materials. However, wet
processes may have difficulty penetrating some constrained trenches
and also may sometimes deform the remaining material. Dry etches
produced in local plasmas formed within the substrate processing
region can penetrate more constrained trenches and exhibit less
deformation of delicate remaining structures. However, local
plasmas may damage the substrate through the production of electric
arcs as they discharge. Additionally, plasma effluents can damage
chamber components that may require replacement or treatment.
[0005] Thus, there is a need for improved systems and methods that
can be used to produce high quality devices and structures. These
and other needs are addressed by the present technology.
SUMMARY
[0006] The present technology includes systems and methods of
etching a semiconductor substrate. Exemplary methods may include
flowing an oxygen-containing precursor into a substrate processing
region of a semiconductor processing chamber. The substrate
processing region may house the semiconductor substrate, and the
semiconductor substrate may include an exposed metal-containing
material. The methods may include flowing ammonia into the
substrate processing region at a temperature above about
200.degree. C. The methods may further include removing an amount
of the metal-containing material.
[0007] In some embodiments the oxygen-containing precursor may be
configured to react with the metal-containing material to produce a
modified metal-containing material. The nitrogen-containing
precursor may be configured to react with the modified
metal-containing material to produce a volatile complex. The
oxygen-containing precursor may be or include one or both of water
or ozone. The pressure within the substrate processing region may
be maintained above or about 10 Torr. The pressure within the
substrate processing region may be maintained above or about 100
Torr. The oxygen-containing precursor and the nitrogen-containing
precursor may be flowed sequentially into the substrate processing
region. The method may also include holding for a first period of
time subsequent flowing the oxygen-containing precursor and prior
to flowing the nitrogen-containing precursor. The first period of
time may be between about 5 seconds and about 30 seconds. The
method may also include holding for a second period of time
subsequent flowing the nitrogen-containing precursor. The second
period of time may be between about 10 seconds and about 60
seconds. The oxygen-containing precursor and the
nitrogen-containing precursor may be halogen free, and the method
may include a plasma-free process. The method is performed at a
temperature of greater than or about 300.degree. C. The process may
be performed in a continuous operation, and the process may remove
greater than or about 4 .ANG./min. The metal-containing material
may be or include titanium nitride.
[0008] The present technology also encompasses methods of etching a
semiconductor substrate. The methods may include removing a native
oxide from a metal-containing material exposed on the semiconductor
substrate. The methods may include flowing ozone into a substrate
processing region housing the semiconductor substrate. The methods
may include holding for a first period of time greater than or
about 1 second. The methods may include flowing a
nitrogen-containing precursor into the substrate processing region.
The methods may include holding for a second period of time greater
than or about 1 second. The methods may also include removing an
amount of the metal-containing material.
[0009] In some embodiments the methods may also include flowing
additional nitrogen-containing precursor into the substrate
processing region. The methods may remove at least about 4 .ANG.
per minute during the method. The nitrogen-containing precursor may
be ammonia. The pressure may be maintained at greater than or about
100 Torr during the method.
[0010] Such technology may provide numerous benefits over
conventional systems and techniques. For example, selectively
removing particular metal-containing materials may allow other
exposed structures to be maintained, which may improve device
integrity. Additionally, the materials utilized may allow the
selective removal of materials that previously could not be readily
removed within a wider processing window than previous
technologies. These and other embodiments, along with many of their
advantages and features, are described in more detail in
conjunction with the below description and attached figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A further understanding of the nature and advantages of the
disclosed technology may be realized by reference to the remaining
portions of the specification and the drawings.
[0012] FIG. 1 shows a top plan view of an exemplary processing
system according to the present technology.
[0013] FIG. 2A shows a schematic cross-sectional view of an
exemplary processing chamber according to embodiments of the
present technology.
[0014] FIG. 2B shows a detailed view of a portion of the processing
chamber illustrated in FIG. 2A according to embodiments of the
present technology.
[0015] FIG. 3 shows a bottom plan view of an exemplary showerhead
according to embodiments of the present technology.
[0016] FIG. 4 shows selected operations in a method of selectively
etching a semiconductor substrate according to the present
technology.
[0017] FIGS. 5A-5B illustrate cross-sectional views of substrate
materials on which selected operations are being performed
according to embodiments of the present technology.
[0018] Several of the figures are included as schematics. It is to
be understood that the figures are for illustrative purposes, and
are not to be considered of scale unless specifically stated to be
of scale. Additionally, as schematics, the figures are provided to
aid comprehension and may not include all aspects or information
compared to realistic representations, and may include additional
or exaggerated material for illustrative purposes.
[0019] In the appended figures, similar components and/or features
may have the same reference label. Further, various components of
the same type may be distinguished by following the reference label
by a letter that distinguishes among the similar components. If
only the first reference label is used in the specification, the
description is applicable to any one of the similar components
having the same first reference label irrespective of the
letter.
DETAILED DESCRIPTION
[0020] The present technology relates to removal of material layers
from semiconductor substrates. During processing, such as mid and
back-end-of-line processing, materials may be removed to expose
underlying structures. The underlying structures may include a
number of materials formed throughout the manufacturing process,
which may be exposed during material removal. For example, hard
mask materials such as titanium nitride may be removed to expose
underlying features, which may include exposed copper,
carbon-containing materials, oxide-containing materials,
nitride-containing materials, low-k dielectrics, and other
materials. Removal of the hard mask material may expose the
underlying materials to etchants that may also react with the
underlying materials. As feature sizes continue to reduce and
aspect ratios continue to increase, wet etchants that may be
tailored to particular materials for removal may no longer be
viable. The surface tension of the etchants applied to the
substrates may deform or collapse the delicate features, which may
cause device failure.
[0021] Dry etchant processes have been developed to attempt to
remove certain materials. These processes may include atomic layer
etching, which may be similar to atomic layer deposition in some
ways, such as the sequential application of precursors to remove
thin layers of material at a time. Conventional atomic layer
etching may utilize a first precursor to modify a surface material,
and a second material to sputter or etch the modified material.
These conventional processes, however, may not be suitable for all
materials, and may damage underlying structures. For example, as
feature sizes are reduced, the amount of any particular material
may become too thin or narrow to allow removal during operations
intended to remove alternative materials. Especially for
back-end-of-line operations, many different materials may be
exposed at a single time, which when contacted by etchants may be
removed in addition to the intended materials. Many conventional
processes utilize halogen-containing etchants, which may etch many
of the exposed materials in addition to the intended layers, or may
etch other exposed materials faster than the intended targets.
Additionally, plasma-based operations may sputter and damage
exposed surfaces or underlying materials at effective plasma
powers.
[0022] The present technology overcomes these deficiencies by
utilizing a cyclic or continuous atomic layer etching process that
may selectively remove certain materials over other exposed
materials on a substrate. For example, the present technology may
selectively remove titanium nitride and tantalum nitride over other
exposed materials to allow the selective removal of hard mask and
other material layers. Some embodiments produce these results by
utilizing a halogen-free and plasma-free process that may
selectively remove certain materials while substantially or
essentially maintaining other material layers. Additionally, some
embodiments may utilize particular chambers to increase an
operating window when certain precursors are utilized. By utilizing
the disclosed atomic layer etching processes, a self-limiting
removal may be performed to allow thin layers of material, such as
monolayers, to be removed during individual cycles, as well as to
allow larger scale continuous removal by expanding an operational
window for the process.
[0023] Although the remaining disclosure will routinely identify
specific semiconductor structures, the present technology may not
be so limited to back-end-of-line hard mask removal. For example,
the selective removal techniques discussed throughout the present
technology may be performed with a variety of high-aspect-ratio
features of semiconductor devices that may include one or more of
the materials discussed. The techniques may obviate additional
etching and removal operations, and may obviate over-deposition of
materials that may be removed but are to be maintained to a certain
thickness after other material removal. Accordingly, the present
technology encompasses selective etching as may be applied in any
number of semiconductor and industry processes beyond those
discussed herein. After identifying one exemplary system in which
the present structures may be formed, the disclosure will discuss
specific structures, as well as methods of performing selective
removal of individual materials utilizing an atomic layer etching
technique.
[0024] FIG. 1 shows a top plan view of one embodiment of a
processing system 100 of deposition, etching, baking, and curing
chambers according to disclosed embodiments. In the figure, a pair
of front opening unified pods (FOUPs) 102 supply substrates of a
variety of sizes that are received by robotic arms 104 and placed
into a low pressure holding area 106 before being placed into one
of the substrate processing chambers 108a-f, positioned in tandem
sections 109a-c. A second robotic arm 110 may be used to transport
the substrate wafers from the holding area 106 to the substrate
processing chambers 108a-f and back. Each substrate processing
chamber 108a-f, can be outfitted to perform a number of substrate
processing operations including the etch processes described herein
in addition to cyclical layer deposition (CLD), atomic layer
deposition (ALD), chemical vapor deposition (CVD), physical vapor
deposition (PVD), etch, pre-clean, degas, orientation, and other
substrate processes.
[0025] The substrate processing chambers 108a-f may include one or
more system components for depositing, annealing, curing and/or
etching material films on the substrate wafer. In one
configuration, two pairs of the processing chamber, e.g., 108c-d
and 108e-f, may be used to deposit dielectric material on the
substrate, and the third pair of processing chambers, e.g., 108a-b,
may be used to etch the deposited dielectric. In another
configuration, all three pairs of chambers, e.g., 108a-f, may be
configured to etch a material on the substrate. Any one or more of
the processes described below may be carried out in chamber(s)
separated from the fabrication system shown in different
embodiments. It will be appreciated that additional configurations
of deposition, etching, annealing, and curing chambers for
dielectric films are contemplated by system 100. Many chambers may
be utilized in the processing system 100, and may be included as
tandem chambers, which may include two similar chambers sharing
precursor, environmental, or control features.
[0026] FIG. 2A shows a cross-sectional view of an exemplary process
chamber system 200 with partitioned plasma generation regions
within the processing chamber. During film etching, e.g., titanium
nitride, tantalum nitride, tungsten, silicon, polysilicon, titanium
oxide, silicon oxide, silicon nitride, silicon oxynitride, silicon
oxycarbide, etc., a process gas may be flowed into the first plasma
region 215 through a gas inlet assembly 205. A remote plasma system
(RPS) 201 may optionally be included in the system, and may process
a first gas which then travels through gas inlet assembly 205. The
inlet assembly 205 may include two or more distinct gas supply
channels where the second channel (not shown) may bypass the RPS
201, if included.
[0027] A cooling plate 203, faceplate 217, ion suppressor 223,
showerhead 225, and a substrate support 265, having a substrate 255
disposed thereon, are shown and may each be included according to
embodiments. The pedestal 265 may have a heat exchange channel
through which a heat exchange fluid flows to control the
temperature of the substrate, which may be operated to heat and/or
cool the substrate or wafer during processing operations. The wafer
support platter of the pedestal 265, which may comprise aluminum,
ceramic, or a combination thereof, may also be resistively heated
in order to achieve relatively high temperatures, such as from up
to or about 100.degree. C. to above or about 1100.degree. C., using
an embedded resistive heater element.
[0028] The faceplate 217 may be pyramidal, conical, or of another
similar structure with a narrow top portion expanding to a wide
bottom portion. The faceplate 217 may additionally be flat as shown
and include a plurality of through-channels used to distribute
process gases. Plasma generating gases and/or plasma excited
species, depending on use of the RPS 201, may pass through a
plurality of holes, shown in FIG. 2B, in faceplate 217 for a more
uniform delivery into the first plasma region 215.
[0029] Exemplary configurations may include having the gas inlet
assembly 205 open into a gas supply region 258 partitioned from the
first plasma region 215 by faceplate 217 so that the gases/species
flow through the holes in the faceplate 217 into the first plasma
region 215. Structural and operational features may be selected to
prevent significant backflow of plasma from the first plasma region
215 back into the supply region 258, gas inlet assembly 205, and
fluid supply system 210. The faceplate 217, or a conductive top
portion of the chamber, and showerhead 225 are shown with an
insulating ring 220 located between the features, which allows an
AC potential to be applied to the faceplate 217 relative to
showerhead 225 and/or ion suppressor 223. The insulating ring 220
may be positioned between the faceplate 217 and the showerhead 225
and/or ion suppressor 223 enabling a capacitively coupled plasma
(CCP) to be formed in the first plasma region. A baffle (not shown)
may additionally be located in the first plasma region 215, or
otherwise coupled with gas inlet assembly 205, to affect the flow
of fluid into the region through gas inlet assembly 205.
[0030] The ion suppressor 223 may comprise a plate or other
geometry that defines a plurality of apertures throughout the
structure that are configured to suppress the migration of
ionically-charged species out of the first plasma region 215 while
allowing uncharged neutral or radical species to pass through the
ion suppressor 223 into an activated gas delivery region between
the suppressor and the showerhead. In embodiments, the ion
suppressor 223 may comprise a perforated plate with a variety of
aperture configurations. These uncharged species may include highly
reactive species that are transported with less reactive carrier
gas through the apertures. As noted above, the migration of ionic
species through the holes may be reduced, and in some instances
completely suppressed. Controlling the amount of ionic species
passing through the ion suppressor 223 may advantageously provide
increased control over the gas mixture brought into contact with
the underlying wafer substrate, which in turn may increase control
of the deposition and/or etch characteristics of the gas mixture.
For example, adjustments in the ion concentration of the gas
mixture can significantly alter its etch selectivity, e.g.,
SiNx:SiOx etch ratios, Si:SiOx etch ratios, etc. In alternative
embodiments in which deposition is performed, it can also shift the
balance of conformal-to-flowable style depositions for dielectric
materials.
[0031] The plurality of apertures in the ion suppressor 223 may be
configured to control the passage of the activated gas, i.e., the
ionic, radical, and/or neutral species, through the ion suppressor
223. For example, the aspect ratio of the holes, or the hole
diameter to length, and/or the geometry of the holes may be
controlled so that the flow of ionically-charged species in the
activated gas passing through the ion suppressor 223 is reduced.
The holes in the ion suppressor 223 may include a tapered portion
that faces the plasma excitation region 215, and a cylindrical
portion that faces the showerhead 225. The cylindrical portion may
be shaped and dimensioned to control the flow of ionic species
passing to the showerhead 225. An adjustable electrical bias may
also be applied to the ion suppressor 223 as an additional means to
control the flow of ionic species through the suppressor.
[0032] The ion suppressor 223 may function to reduce or eliminate
the amount of ionically charged species traveling from the plasma
generation region to the substrate. Uncharged neutral and radical
species may still pass through the openings in the ion suppressor
to react with the substrate. It should be noted that the complete
elimination of ionically charged species in the reaction region
surrounding the substrate may not be performed in embodiments. In
certain instances, ionic species are intended to reach the
substrate in order to perform the etch and/or deposition process.
In these instances, the ion suppressor may help to control the
concentration of ionic species in the reaction region at a level
that assists the process.
[0033] Showerhead 225 in combination with ion suppressor 223 may
allow a plasma present in first plasma region 215 to avoid directly
exciting gases in substrate processing region 233, while still
allowing excited species to travel from chamber plasma region 215
into substrate processing region 233. In this way, the chamber may
be configured to prevent the plasma from contacting a substrate 255
being etched. This may advantageously protect a variety of
intricate structures and films patterned on the substrate, which
may be damaged, dislocated, or otherwise warped if directly
contacted by a generated plasma. Additionally, when plasma is
allowed to contact the substrate or approach the substrate level,
the rate at which oxide species etch may increase. Accordingly, if
an exposed region of material is oxide, this material may be
further protected by maintaining the plasma remotely from the
substrate.
[0034] The processing system may further include a power supply 240
electrically coupled with the processing chamber to provide
electric power to the faceplate 217, ion suppressor 223, showerhead
225, and/or pedestal 265 to generate a plasma in the first plasma
region 215 or processing region 233. The power supply may be
configured to deliver an adjustable amount of power to the chamber
depending on the process performed. Such a configuration may allow
for a tunable plasma to be used in the processes being performed.
Unlike a remote plasma unit, which is often presented with on or
off functionality, a tunable plasma may be configured to deliver a
specific amount of power to the plasma region 215. This in turn may
allow development of particular plasma characteristics such that
precursors may be dissociated in specific ways to enhance the
etching profiles produced by these precursors.
[0035] A plasma may be ignited either in chamber plasma region 215
above showerhead 225 or substrate processing region 233 below
showerhead 225. Plasma may be present in chamber plasma region 215
to produce the radical precursors from an inflow of, for example, a
fluorine-containing precursor or other precursor. An AC voltage
typically in the radio frequency (RF) range may be applied between
the conductive top portion of the processing chamber, such as
faceplate 217, and showerhead 225 and/or ion suppressor 223 to
ignite a plasma in chamber plasma region 215 during deposition. An
RF power supply may generate a high RF frequency of 13.56 MHz but
may also generate other frequencies alone or in combination with
the 13.56 MHz frequency.
[0036] FIG. 2B shows a detailed view 253 of the features affecting
the processing gas distribution through faceplate 217. As shown in
FIGS. 2A and 2B, faceplate 217, cooling plate 203, and gas inlet
assembly 205 intersect to define a gas supply region 258 into which
process gases may be delivered from gas inlet 205. The gases may
fill the gas supply region 258 and flow to first plasma region 215
through apertures 259 in faceplate 217. The apertures 259 may be
configured to direct flow in a substantially unidirectional manner
such that process gases may flow into processing region 233, but
may be partially or fully prevented from backflow into the gas
supply region 258 after traversing the faceplate 217.
[0037] The gas distribution assemblies such as showerhead 225 for
use in the processing chamber section 200 may be referred to as
dual channel showerheads (DCSH) and are additionally detailed in
the embodiments described in FIG. 3. The dual channel showerhead
may provide for etching processes that allow for separation of
etchants outside of the processing region 233 to provide limited
interaction with chamber components and each other prior to being
delivered into the processing region.
[0038] The showerhead 225 may comprise an upper plate 214 and a
lower plate 216. The plates may be coupled with one another to
define a volume 218 between the plates. The coupling of the plates
may be so as to provide first fluid channels 219 through the upper
and lower plates, and second fluid channels 221 through the lower
plate 216. The formed channels may be configured to provide fluid
access from the volume 218 through the lower plate 216 via second
fluid channels 221 alone, and the first fluid channels 219 may be
fluidly isolated from the volume 218 between the plates and the
second fluid channels 221. The volume 218 may be fluidly accessible
through a side of the gas distribution assembly 225.
[0039] FIG. 3 is a bottom view of a showerhead 325 for use with a
processing chamber according to embodiments. Showerhead 325 may
correspond with the showerhead 225 shown in FIG. 2A. Through-holes
365, which show a view of first fluid channels 219, may have a
plurality of shapes and configurations in order to control and
affect the flow of precursors through the showerhead 225. Small
holes 375, which show a view of second fluid channels 221, may be
distributed substantially evenly over the surface of the
showerhead, even amongst the through-holes 365, and may help to
provide more even mixing of the precursors as they exit the
showerhead than other configurations.
[0040] Turning to FIG. 4 is shown selected operations in a method
400 of selectively etching a metal-containing material, one or more
of which may be performed, for example, in the chamber 200 as
previously described, or in different chambers. Method 400 may
utilize particular precursor combinations to allow both plasma and
non-plasma etching within chamber 200, which may be characterized
by a wider operating window than many conventional chambers. Method
400 may include one or more operations prior to the initiation of
the method, including front-end processing, deposition, etching,
polishing, cleaning, or any other operations that may be performed
prior to the described operations. A processed substrate, which may
be a semiconductor wafer of any size, may be positioned within a
chamber for the method 400. In embodiments the operations of method
400 may be performed in multiple chambers depending on the
operations being performed. Additionally, in embodiments the entire
method 400 may be performed in a single chamber to reduce queue
times, contamination issues, and vacuum break. Subsequent
operations to those discussed with respect to method 400 may also
be performed in the same chamber or in different chambers as would
be readily appreciated by the skilled artisan.
[0041] Movement of a substrate from deposition or other processing
locations may produce a native oxide layer on exposed
metal-containing layers. In some embodiments, method 400 may
include removing a native oxide layer, which may be titanium oxide,
from exposed layers of material to be processed. In some
conventional technologies, native oxides may cause reductions in
etching selectivities as the oxide may etch differently from the
material over which the oxide has formed. For example, method 400
may in some embodiments be performed to remove titanium nitride
selectively to other exposed materials. However, when a native
oxide is formed overlying the titanium nitride, the etchants
utilized in the present technology may be characterized by
different selectivity toward titanium oxide relative to other
exposed materials. Thus, if untreated, the etch process may remove
other exposed materials at least partially during a breakthrough of
the exposed oxide.
[0042] By utilizing chambers such as chamber 200 described above,
the native oxide may be removed in operation 403, when performed. A
remote plasma operation may be performed as previously described to
selectively remove exposed oxide overlying a material to be etched,
such as titanium nitride. A fluorine-containing precursor may be
utilized to remove the oxide in some embodiments. Additionally, a
non-plasma process may be performed in which an etchant such as
hydrogen fluoride may be delivered to remove the titanium oxide.
Although operation 403, when performed, may utilize one or both of
a halogen-containing precursor or plasma, the remaining operations
may be performed without plasma processing, and may not utilize any
fluorine-containing precursors as will be described further
below.
[0043] Once an underlying material has been exposed, either after
operation 403 or when no native oxide has occurred, method 400 may
include flowing an oxygen-containing precursor into a substrate
processing region of a semiconductor processing chamber at
operation 405. The semiconductor substrate may include one or more
exposed regions of metal-containing material, and may include at
least one other exposed material in embodiments, although multiple
materials may be exposed on a substrate including the
metal-containing material. Method 400 may optionally include
performing a process hold at operation 410, which may allow time
for the oxygen-containing precursor to interact or react with the
metal-containing material. The hold may be performed for a first
period of time.
[0044] The method may additionally include flowing a
nitrogen-containing precursor into the substrate processing region
at operation 415. The nitrogen-containing precursor may be flowed
subsequent to the flow of the oxygen-containing precursor, such as
in a sequential manner, and the nitrogen-containing precursor may
be flowed subsequent the first period of time of the process hold.
A second process hold may optionally be performed at operation 420
subsequent flowing the nitrogen-containing precursor. The second
process hold may be performed for a second period of time to allow
the nitrogen-containing precursor to react or interact with the
metal-containing material. In some embodiments certain operations
may be repeated in a number of cycles. For example, one or more of
operations 405, 410, 415, or 420 may be repeated a number of times.
In some embodiments delivery of the oxygen-containing precursor and
the nitrogen-containing precursor may be performed simultaneously
and in a continuous manner in which a pump is engaged within the
processing chamber to remove etchant species and byproducts. At
operation 425, an amount of the metal-containing material may be
removed from the semiconductor substrate. Additional operations may
also be included such as purging excess precursor with an inert
precursor or pumping excess precursor or removed metal-containing
material from the processing region or chamber.
[0045] As previously discussed, the present technology may perform
an atomic layer removal of material from a semiconductor substrate
in either a cyclic or continuous manner. The first precursor flowed
may interact with a surface layer of the metal-containing material
to produce a modified metal-containing material. In one
non-limiting example, the oxygen-containing precursor may react
with a hard mask material, such as titanium nitride, to oxidize an
amount of the metal-containing material. This modification may
occur only at a surface level of the metal-containing material, or
may occur to a controlled depth within the metal-containing
material. For example, the metal-containing material may be
modified, such as oxidized, to a first depth within the
metal-containing material. In some embodiments, the
metal-containing material may be modified greater than, about, or
less than 10 nm. In some embodiments, the metal-containing material
may be modified less than or about 9 nm, less than or about 8 nm,
less than or about 7 nm, less than or about 6 nm, less than or
about 5 nm, less than or about 4 nm, less than or about 3 nm, less
than or about 2 nm, less than or about 1 nm, less than or about 9
.ANG., less than or about 8 .ANG., less than or about 7 .ANG., less
than or about 6 .ANG., less than or about 5 .ANG., less than or
about 4 .ANG., less than or about 3 .ANG., less than or about 2
.ANG., less than or about 1 .ANG., less than or about 0.9 .ANG.,
less than or about 0.8 .ANG., less than or about 0.7 .ANG., less
than or about 0.6 .ANG., less than or about 0.5 A, less than or
about 0.4 .ANG., less than or about 0.3 .ANG., less than or about
0.2 .ANG., less than or about 0.1 .ANG., or less, and may be
modified at only a single layer or monolayer of the structure. For
example, only a top monolayer of the metal-containing material may
be modified in embodiments.
[0046] The oxygen-containing material may be purged from the
processing region in some embodiments prior to the introduction of
the nitrogen-containing precursor, although in other embodiments
the precursors may be delivered together. The purge may occur by a
pumping system of the chamber that removes unreacted precursors
from the substrate processing region, for example. Also, the
oxygen-containing precursor may be pulsed into the chamber to limit
the amount of oxygen-containing precursor utilized, or to limit or
control the amount of interaction between the oxygen-containing
precursor and the metal-containing material. The
nitrogen-containing precursor may be subsequently flowed into the
substrate processing region to interact with the modified
metal-containing material in embodiments. The nitrogen-containing
precursor may react with modified portions of the metal-containing
material, while having limited or no interaction with unmodified
portions of the metal-containing material.
[0047] The nitrogen-containing precursor may produce a complex of
the modified metal-containing material, and in embodiments, this
complex may be volatile. The volatile material may desorb from the
surface of the metal-containing material, which may produce the
material removal discussed above. The amount of removal may be
determined by the amount of modified material produced by the first
precursor, such as an oxygen-containing precursor. The second
precursor, such as the nitrogen-containing precursor, may
preferentially or exclusively react with modified material to
produce a volatile complex that may be removed. In this way, method
400 may provide a self-limiting removal, where modified material
may be removed from the surface of the substrate, or from the
surface of the metal-containing material, while unmodified material
remains. Once the modified material has been removed from the
surface, no further reaction may occur from the nitrogen-containing
precursor.
[0048] The oxygen-containing precursor may be or include any
material including oxygen. These materials may include oxygen,
water, ozone, nitrogen-and-oxygen-containing precursors, and other
materials that may include oxygen in the chemical structure. The
oxygen-containing precursor may be flowed through a plasma prior to
delivery to the substrate, and in alternative embodiments the
oxygen-containing precursor may not be flowed through a plasma
prior to delivery to the substrate. For example, a plasma may be
formed from an oxygen-containing precursor, such as oxygen, and the
plasma effluents may be flowed to the substrate for interaction
with the metal-containing materials. In other embodiments an
oxygen-containing precursor, such as water or water vapor, may be
flowed directly to the substrate to interact with the
metal-containing material. Ozone may be used in some embodiments,
which may allow a non-plasma operation to be performed.
Additionally, because of the stability of ozone and water vapor, an
enhanced operating window may be used to increase selectivity
and/or reduce etch time of the process.
[0049] The nitrogen-containing precursor may be any
nitrogen-containing material, and in some embodiments, the
nitrogen-containing precursor may be or include ammonia. The
ammonia may react with an oxidized metal-containing material to
produce a complex, which may be a volatile complex. Based on
process conditions discussed below, the volatile complex may desorb
from the surface of the metal-containing material and be removed
from the chamber. Any of a variety of nitrogen-containing
precursors may be used in some embodiments, however the use of
ammonia may increase the operating range in which method 400 may be
performed. Many amines may have a limited operating window both for
temperature and pressure, and may begin to decompose at increased
temperature. However, temperature may allow increased processing
speed, which may facilitate high selectivity etching of the
metal-containing material in some embodiments. For example, and as
will be explained further below, operating temperatures above or
about 300.degree. C. may increase etch amounts to several angstrom
per minute, when ammonia is utilized as a precursor. Other amines,
however, may be incapable of operating at such temperatures. For
example, many amines may begin to decompose at temperatures above
or about 300.degree. C., and as one example, diethylamine may
auto-ignite above 300.degree. C. Accordingly, by utilizing ammonia
as opposed to other amines, processing temperatures and pressures
may be increased and performed over a broader range, which may
provide increased control over the operating methods and removal
characteristics.
[0050] In some embodiments the nitrogen-containing materials may be
or include Lewis bases and/or halogen-containing precursors or
ligands. The halogens may include fluorine or chlorine, for
example, and the halogen may be coupled with any number of
structural moieties including organic and inorganic materials or
structures. For example, the additional ligands may include simple
anions, which may include hydrogen or fluorine, for example.
Additionally, the materials may be or include lone-pair-containing
species, such as water, ammonia as described above, as well as
hydroxyl and methyl-containing materials or anions. More complex
anions including sulfates may be used, along with other
electron-rich pi-system Lewis bases, which may include ethyne,
ethene, and benzene, for example. In some embodiments additional
materials may include nitrogen trifluoride or sulfur hexafluoride,
as well as other materials characterized by similar properties. The
addition or inclusion of these materials may improve etch rates for
some metal materials, such as titanium nitride, for example.
[0051] The oxygen-containing precursor and the nitrogen-containing
precursor may be flowed sequentially into the substrate processing
region, and the flow of each material may be a pulsed delivery into
the processing chamber. The time of each pulse may be similar or
different between the oxygen-containing precursor and the
nitrogen-containing precursor, and may be similar or different
between cycles of the method as well. The pulse time for any of the
precursors may be less than or about 30 seconds in embodiments, and
may be less than or about 20 seconds, less than or about 10
seconds, less than or about 8 seconds, less than or about 6
seconds, less than or about 4 seconds, less than or about 2
seconds, less than or about 1 seconds, less than or about 0.9
seconds, less than or about 0.8 seconds, less than or about 0.7
seconds, less than or about 0.6 seconds, less than or about 0.5
seconds, less than or about 0.4 seconds, less than or about 0.3
seconds, less than or about 0.2 seconds, less than or about 0.1
seconds, or less in embodiments. Because some embodiments may seek
to remove only a monolayer or a few monolayers of material with
each cycle, the pulse time may be between about 0.1 seconds and
about 5 seconds in embodiments, or may be between about 0.1 seconds
and about 2 seconds, or between about 0.1 seconds and 1 second in
embodiments. As previously noted, in some embodiments the
precursors may be flowed continuously into the processing chamber
to allow a continuous removal of material.
[0052] The amount of time during which the hold operations are
performed may also affect etch rate and amount. For example, the
longer the hold time, the more metal-containing material may be
modified. Accordingly, in embodiments, the hold time may be greater
than or about 1 second in embodiments, and may be greater than or
about 5 seconds, greater than or about 10 seconds, greater than or
about 15 seconds, greater than or about 20 seconds, greater than or
about 25 seconds, greater than or about 30 seconds, greater than or
about 35 seconds, greater than or about 40 seconds, greater than or
about 45 seconds, greater than or about 50 seconds, greater than or
about 55 seconds, greater than or about 60 seconds, or longer. The
hold time may be affected by the amount of precursor utilized in
embodiments. For example, a plateau may occur in the amount of
material modified or removed during either of the hold times, which
may indicate the end of either of the half-reactions or removal in
the method. The time held for each operation may be adjusted up or
down based on the occurrence of such a plateau to limit the effect
on queue times for the method.
[0053] Process conditions may affect one or more aspects of the
methods of the present technology. Temperature may be adjusted to
cause, increase the efficiency of, or otherwise contribute to the
operations of the method. One or more operations of method 400 may
be performed at a temperature greater than or about 80.degree. C.
In some embodiments, the temperature may be greater than or about
90.degree. C., greater than or about 100.degree. C., greater than
or about 120.degree. C., greater than or about 140.degree. C.,
greater than or about 160.degree. C., greater than or about
180.degree. C., greater than or about 200.degree. C., greater than
or about 220.degree. C., greater than or about 240.degree. C.,
greater than or about 260.degree. C., greater than or about
280.degree. C., greater than or about 300.degree. C., greater than
or about 320.degree. C., greater than or about 340.degree. C.,
greater than or about 360.degree. C., greater than or about
380.degree. C., greater than or about 400.degree. C., greater than
or about 420.degree. C., greater than or about 440.degree. C.,
greater than or about 460.degree. C., greater than or about
480.degree. C., greater than or about 500.degree. C., greater than
or about 520.degree. C., greater than or about 540.degree. C.,
greater than or about 560.degree. C., greater than or about
580.degree. C., greater than or about 600.degree. C., or higher. In
embodiments the temperature may be any temperature included within
one of these ranges, or a smaller range encompassed by any of these
ranges or noted temperatures.
[0054] By maintaining the temperature above or about 100.degree. C.
or above or about 200.degree. C. in embodiments, additional energy
sources to initiate one or more of the reactions may not be needed.
Additionally, temperatures above about 100.degree. C. may allow the
complex formed between the modified or oxidized metal-containing
material to desorb from the surface of the metal-containing
material. Upon contact of the nitrogen-containing precursor to the
modified or oxidized metal-containing material, the volatile
complex may be formed and desorbed simultaneously, and then may be
removed from the processing region or chamber.
[0055] Additional chamber conditions including pressure may be
adjusted to affect the operations being performed, such as the etch
rate of the metal-containing material. The pressure within the
chamber may be maintained between about 50 mTorr and about 760 Torr
in embodiments. The pressure may also be maintained above or about
5 Torr, above or about 50 Torr, above or about 100 Torr, above or
about 150 Torr, above or about 200 Torr, above or about 250 Torr,
above or about 300 Torr, above or about 350 Torr, above or about
400 Torr, above or about 450 Torr, above or about 500 Torr, above
or about 550 Torr, above or about 600 Torr, above or about 650
Torr, above or about 700 Torr, or greater. Etch amounts may scale
in some embodiments with increased pressure. By performing the etch
processes at higher pressures, such as listed, the present
technology may be capable of performing method 400 at increased
rates, such as at tens of angstrom of material removed per minute.
Additionally, by utilizing precursors such as ozone and ammonia,
the precursors can remain stable at increased temperature and/or
pressure to perform the etch processes.
[0056] The pressure may be adjusted based on the pulse time of any
of the precursors. For example, increasing the pulse time of a
precursor may increase the pressure within the chamber. The
pressure may be reduced subsequent a pulse of material, by pumping
down the chamber, or may be maintained at an increased pressure.
For example, by increasing the pulse time of water vapor, the
overall etch time may not be affected. However, increasing the
pulse time and the pressure within the processing region may
increase the thickness of the oxide layer formed on the
metal-containing material. For example, by increasing the
oxygen-containing precursor pulse time from about 0.5 seconds to
about 2 seconds and allowing the pressure to increase from about
100 Torr to about 150 Torr may increase the oxide thickness by over
2 nm, and may increase the thickness by over 3 nm or more.
[0057] The amount of nitrogen-containing precursor may affect the
etch rate of the process and may depend on the oxide thickness
formed on the metal-containing material. For example, a pulse of
nitrogen-containing precursor may only remove a certain amount of
modified metal-containing material. However, by flowing additional
nitrogen-containing precursor into the processing region, a further
amount of modified metal-containing material may be removed if
there is residual modified material that was not fully removed with
the first pulse of nitrogen-containing precursor. Accordingly,
process queue times may be reduced by modifying the
metal-containing material to a greater depth, and then performing
multiple cycles of the nitrogen-containing precursor delivery to
sequentially etch and remove layers of the modified
metal-containing material. Thus, for every one operation of flowing
the oxygen-containing precursor into the processing chamber and
performing a hold for a first period of time, multiple operations
of flowing the nitrogen-containing precursor may be performed.
Additionally, when performed in chamber such as processing chamber
200, a continuous flow of the nitrogen-containing precursor may be
performed while pumping out etch byproducts to further increase
etch rates and amounts.
[0058] Each operation of flowing the nitrogen-containing precursor
may include performing a hold as discussed above, such that both
flowing the nitrogen-containing precursor and performing a hold for
a second period of time may be performed. In some embodiments, for
each operation of flowing the oxygen-containing precursor into the
processing region, the operation of flowing the nitrogen-containing
precursor may be repeated one or more times, and may be repeated at
least 2 times, at least 3 times, at least 4 times, at least 5
times, at least 6 times, at least 7 times, at least 8 times, at
least 9 times, at least 10 times, at least 11 times, at least 12
times, at least 13 times, at least 14 times, at least 15 times, or
more depending on the depth of the modification, such as oxidation
to the metal-containing material.
[0059] The total number of cycles of any operation of method 400,
including either or both of flowing the oxygen-containing precursor
and flowing the nitrogen-containing precursor, along with any
accompanying hold period, may be based on a desired depth of
etching of the metal-containing material. For example, each cycle
of method 400 may etch a certain amount of metal-containing
material, and may etch at least about 0.05 .ANG. per cycle. In some
embodiments, method 400 may etch at least about 0.1 .ANG. per
cycle, and may etch at least about 0.12 .ANG. per cycle, at least
about 0.14 .ANG. per cycle, at least about 0.16 .ANG. per cycle, at
least about 0.18 .ANG. per cycle, at least about 0.2 .ANG. per
cycle, at least about 0.22 .ANG. per cycle, at least about 0.24
.ANG. per cycle, at least about 0.26 .ANG. per cycle, at least
about 0.28 .ANG. per cycle, at least about 0.3 .ANG. per cycle, at
least about 0.32 .ANG. per cycle, at least about 0.34 .ANG. per
cycle, at least about 0.36 .ANG. per cycle, at least about 0.38
.ANG. per cycle, at least about 0.4 .ANG. per cycle, at least about
0.42 .ANG. per cycle, at least about 0.44 .ANG. per cycle, at least
about 0.46 .ANG. per cycle, at least about 0.48 .ANG. per cycle, at
least about 0.5 .ANG. per cycle, or more. When performed at higher
pressures and temperatures, or as cycling time is reduced towards a
more continuous etch process, etch rates may increase allowing
removals of greater than or about 5 .ANG. per minute, greater than
or about 10 .ANG. per minute, greater than or about 25 .ANG. per
minute, greater than or about 50 .ANG. per minute, greater than or
about 70 .ANG. per minute, greater than or about 100 .ANG. per
minute, or more. Thus, for removals that may be up to or over 50 nm
or more, while previous technologies may have taken several hours
for removal, the present technology may allow removal in less than
an hour, and in some embodiments less than 30 minutes, less than or
about 20 minutes, less than or about 10 minutes, or less.
[0060] In embodiments where multiple pulses of the
nitrogen-containing precursor are flowed into the processing region
for each pulse of oxygen-containing precursor, the amount of
material etched per cycle of nitrogen-containing precursor may be
any of the etch rates noted above. Atomic layer deposition may be
performed to deposit any of the materials formed on the substrate,
and may be used in general to produce a more conformal layer of
material. Depending on the material being deposited and the process
conditions, the growth rate may be about 0.35 .ANG. per cycle of
precursors. The present technology has been shown to be capable of
performing an atomic layer etch of metal-containing materials that
is characterized by an etch rate that is similar to or greater than
the corresponding growth rates.
[0061] Other deposition methods may produce different etch rates as
well. For example, physical vapor deposition may produce etch rates
that are less than etch rates for materials formed with atomic
layer deposition. Because physical vapor deposition often produces
higher quality or denser films than atomic layer deposition, the
amount of material removed per cycle of method 400 may be lower for
such films. Accordingly, the number of cycles of method 400
performed may be greater depending on the quality of the film to be
removed. The overall number of cycles of method 400 performed may
be related to the depth of metal-containing material to be removed,
but may be more than or about 5 cycles in embodiments, although in
other embodiments a continuous removal may be performed.
Additionally, aspects of method 400 may be repeated in at least
about 10 cycles, at least about 20 cycles, at least about 50
cycles, at least about 75 cycles, at least about 100 cycles, at
least about 150 cycles, at least about 200 cycles, at least about
250 cycles, at least about 300 cycles, at least about 350 cycles,
at least about 400 cycles, at least about 450 cycles, at least
about 500 cycles, at least about 550 cycles, at least about 600
cycles, at least about 650 cycles, at least about 700 cycles, at
least about 750 cycles, at least about 800 cycles, at least about
850 cycles, at least about 900 cycles, at least about 950 cycles,
at least about 1,000 cycles, or more depending on the amount of
material to be removed. Both flowing and/or holding operations may
be repeated per cycle, or certain operations may be repeated per
cycle in embodiments. For example, for each cycle of flowing the
oxygen-containing precursor, flowing the nitrogen-containing
precursor may be repeated at least 10 times, and thus for 50 total
cycles of flowing the oxygen-containing precursor, flowing the
nitrogen-containing precursor may be repeated about 500 total
cycles.
[0062] In some embodiments, the present technology may provide a
halogen-free and plasma-free process for removing one or more
metal-containing materials with an atomic layer etching that may be
self-limiting. One, both, or all precursors used in method 400 may
be halogen-free in embodiments, which may allow a more selective
etch of metal-containing materials with respect to other exposed
materials on the substrate surface. Additionally, method 400 may be
performed in a plasma-free environment, and may involve no plasma
precursors in embodiments. Radical precursors may interact with
exposed materials in a physical manner that may sputter or
otherwise etch materials on the surface irrespective of the film
composition. By minimizing or eliminating plasma effluents within
the processing region and chamber, a chemical-based etch may be
performed that may allow selective etching of the metal-containing
material over other materials on the substrate.
[0063] In embodiments plasma precursors may be utilized in one or
more operations depending on the exposed materials on the
substrate, and an amount of etching that may be acceptable on
materials to be maintained during the etching process. Some
materials may be formed or deposited to increased thickness in
previous operations that may accommodate an amount of removal with
respect to the metal-containing material intended to be etched.
Plasma effluents may be produced externally to the processing
chamber, or within the processing chamber. A remote plasma unit may
be fluidly coupled with the processing chamber, and may provide
radical effluents to the substrate. Within the processing chamber
plasma may be formed at the substrate level, or may be produced in
a region of the chamber physically separate from but fluidly
coupled with the substrate processing region. By producing plasma
remotely from the substrate, a sputtering component from plasma
particles may be limited. For example, plasma may be produced in a
capacitively-coupled, inductively-coupled, microwave, or other
plasma formed upstream of the substrate processing region prior to
flowing the plasma effluents into the substrate processing
region.
[0064] One or more precursors may be excited via a plasma process,
including carrier gases that may be flowed with the precursors. In
some embodiments an oxygen-containing precursor may be flowed into
a remote plasma region where a plasma may be formed to produce
radical effluents. The plasma effluents may be provided to the
substrate processing region, such as through a faceplate or
showerhead as discussed previously, and may interact with the
substrate including exposed regions of the metal-containing
material. The plasma effluents may oxidize or assist in oxidizing
the metal-containing material. The plasma may be formed from any
oxygen-containing precursor, such as oxygen in embodiments, and may
be used with or alternatively to water vapor or other
oxygen-containing precursors. For example, the oxygen-containing
plasma effluents may be used alone or may be used in conjunction
with a water pulse as previously discussed. A water pulse may be
provided to the substrate processing region and then
oxygen-containing plasma effluents may be delivered to the
processing region to further interact with the substrate
surfaces.
[0065] As noted the plasma precursors may interact with any exposed
materials on the surface of the substrate, and so in embodiments
where additional material removal may be limited, the process may
be performed plasma free. The plasma used in some embodiments may
also be a low-power plasma, and may be below about 1000 W.
Additionally, the plasma power applied to the oxygen-containing
precursor may be below or about 900 W, below or about 800 W, below
or about 700 W, below or about 600 W, below or about 500 W, below
or about 400 W, below or about 300 W, below or about 200 W, below
or about 100 W, or less in embodiments.
[0066] Turning to FIGS. 5A-5B are shown cross-sectional views of
substrate materials on which selected operations are being
performed according to embodiments of the present technology, which
may include back-end-of-line hard mask removal. The substrates may
include layered regions of oxide, nitride, polysilicon, copper,
black diamond, low-k dielectric, or other materials as would be
understood by the skilled artisan. The simplified schematic
illustrated in FIG. 5A includes a substrate 505 having a
metal-containing material 510a formed on regions of the substrate
505. Although not illustrated, the substrate may include exposed
regions of many different materials as discussed above along with
exposed regions of hard mask material such as metal-containing
material 510a. The metal-containing material may be residual
material for removal subsequent a patterning process, for example.
The removal may be performed according to the present technology,
which may allow etching of the metal-containing material without or
with limited effect on other exposed materials.
[0067] The removal process may involve exposing metal-containing
material 510a to an oxygen-containing precursor, such as water
vapor or some other oxygen-containing material. The
oxygen-containing precursor may modify or oxidize the
metal-containing material 510a to a depth that may be up to or
about 0.1 .ANG. in embodiments, and may be greater than or about
0.12 .ANG., greater than or about 0.14 .ANG., greater than or about
0.16 .ANG., greater than or about 0.18 .ANG., greater than or about
0.2 .ANG., greater than or about 0.22 .ANG., greater than or about
0.24 .ANG., greater than or about 0.26 .ANG., greater than or about
0.28 .ANG., greater than or about 0.3 .ANG., greater than or about
0.32 .ANG., greater than or about 0.34 .ANG., greater than or about
0.36 .ANG., greater than or about 0.38 .ANG., greater than or about
0.4 .ANG., or greater, and may be any range between any two of
these listed numbers or within a smaller range encompassed by any
of these ranges.
[0068] To allow adequate time for interaction, the
oxygen-containing precursor may be maintained within the substrate
processing region for a period of time as discussed above.
Remaining or unreacted oxygen-containing precursor may be purged
from the chamber in embodiments. Subsequently, a
nitrogen-containing precursor, such as ammonia as previously
discussed, may be delivered to the processing region, where it may
interact or react with the modified or oxidized portion of the
metal-containing material 510a. This interaction may produce a
volatile complex that desorbs from the surface of the substrate and
metal-containing material at processing temperatures, and may be
purged from the processing region of the chamber. As illustrated in
FIG. 5B, metal-containing material 510b has been reduced while
substrate 505 has limited modification, which may be substantially
or essentially no interaction.
[0069] The process may be repeated for a number of cycles as
previously discussed to remove additional metal-containing
material, and may remove all metal-containing material in
embodiments.
[0070] In embodiments the metal-containing material may be titanium
nitride, and may be or include other nitride or metal-containing
materials. Additionally exposed materials may include silicon
oxide, hafnium oxide, other metal oxides, black diamond or other
low-k dielectrics, copper or other metals, nitride materials such
as tantalum nitride, etc. Methods according to the present
technology may selectively etch titanium nitride with respect to
these other materials. In embodiments, titanium nitride may be
etched at a selectivity greater than or about 10:1 with respect to
most other materials, and may be etched at a selectivity greater
than or about 20:1, greater than or about 30:1, greater than or
about 40:1, greater than or about 50:1, greater than or about 60:1,
greater than or about 70:1, greater than or about 80:1, greater
than or about 90:1, greater than or about 100:1, or greater, and in
some embodiments, there may be substantially or essentially no loss
for other materials on the substrate, providing complete
selectivity between titanium nitride and these other materials.
[0071] Tantalum nitride may be characterized by an amount of etch
loss with respect to titanium nitride over 500 cycles of atomic
layer etching according to the present technology. While greater
than 15 nm of titanium nitride may be etched with the technology,
tantalum nitride may display less than 2 nanometers of removal.
Depending on the number of cycles performed, titanium nitride may
be etched respective to tantalum nitride with a selectivity greater
than or about 5:1, greater than or about 6:1, greater than or about
7:1, greater than or about 8:1, greater than or about 9:1, greater
than or about 10:1, greater than or about 12:1, greater than or
about 15:1, or more. Additionally, tantalum nitride may be etched
respective to the other listed materials at a selectivity of any of
the numbers previously stated depending on the number of cycles
performed, as the process of the present technology additionally
etched tantalum nitride while substantially maintaining the other
materials.
[0072] In the preceding description, for the purposes of
explanation, numerous details have been set forth in order to
provide an understanding of various embodiments of the present
technology. It will be apparent to one skilled in the art, however,
that certain embodiments may be practiced without some of these
details, or with additional details.
[0073] Having disclosed several embodiments, it will be recognized
by those of skill in the art that various modifications,
alternative constructions, and equivalents may be used without
departing from the spirit of the embodiments. Additionally, a
number of well-known processes and elements have not been described
in order to avoid unnecessarily obscuring the present technology.
Accordingly, the above description should not be taken as limiting
the scope of the technology.
[0074] Where a range of values is provided, it is understood that
each intervening value, to the smallest fraction of the unit of the
lower limit, unless the context clearly dictates otherwise, between
the upper and lower limits of that range is also specifically
disclosed. Any narrower range between any stated values or unstated
intervening values in a stated range and any other stated or
intervening value in that stated range is encompassed. The upper
and lower limits of those smaller ranges may independently be
included or excluded in the range, and each range where either,
neither, or both limits are included in the smaller ranges is also
encompassed within the technology, subject to any specifically
excluded limit in the stated range. Where the stated range includes
one or both of the limits, ranges excluding either or both of those
included limits are also included.
[0075] As used herein and in the appended claims, the singular
forms "a", "an", and "the" include plural references unless the
context clearly dictates otherwise. Thus, for example, reference to
"a layer" includes a plurality of such layers, and reference to
"the precursor" includes reference to one or more precursors and
equivalents thereof known to those skilled in the art, and so
forth.
[0076] Also, the words "comprise(s)", "comprising", "contain(s)",
"containing", "include(s)", and "including", when used in this
specification and in the following claims, are intended to specify
the presence of stated features, integers, components, or
operations, but they do not preclude the presence or addition of
one or more other features, integers, components, operations, acts,
or groups.
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